In the past, a non orientated collagen was used as a substrate material of a cell culture for many years. On the contrary, although a collagen having an orientation is found in tremendous numbers in the human body, a collagen/apatite of a bone is also orientated according to the site of the bone, it has been thought that the orientation of a collagen/apatite plays a role in functions of growth and strength etc., of a bone.
As a method of a collagen substrate having an orientation, it is generally known a method of applying a powerful magnetic field to it during a process of formation of a collagen fiber (JP-A-2006-280222, “Patent Literature 1”). Further, it is also known a method of spin-coating a collagen gel (JP-A-2010-148691, “Patent Literature 2”).
Further, as a method of producing a hard tissue of a living organism which resembles a bone etc., by calcifying a collagen, a method of seeding an osteoblast is generally known (JP-A-2005-278909, “Patent Literature 3”).
As a method of synthesizing a hydroxyapatite which is known as a main component of a bone or a tooth other than the method of seeding an osteoblast, a method of dipping a substrate such as high-polymer materials to calcium solution and phosphoric acid solution alternately is suggested (JP-A-2000-327314, “Patent Literature 4;” T. Taguchi, A. Kishida, M. Akashi, Hydroxyapatite Formation on/in Poly(vinyl alcohol) Hydrogel Matrices using a Novel Alternate Soaking Process(I), Chem. Lett., pp. 711-712, 1998, “Nonpatent Literature 1”).
Furthermore, as a method of controlling an orientation of apatite, a method of producing a collagen/apatite complex according to a simultaneous titration coprecipitation method is suggested (JP-A1-2004-041320, “Patent Literature 5;” M. Kikuchi, S. Ito, S. Ichinose, K. Shinomiya, J. Tanaka. Self-organization mechanism in a bone-like hydroxyapatite/collagen nanocomposites synthesized in vitro and its biological reaction in vivo, Biomaterials, Vol. 22, pp. 1705-1711, 2001, “Nonpatent Literature 2”).